Of interest is commonly owned copending application entitled X-ray Tube, Ser. No. 07/618,350, filed Nov. 26, 1990 in the name of Rolf Golitzer and Lothar Weil.
The invention relates to a rotary-anode X-ray tube comprising a sleeve bearing, for journalling the rotary anode in the axial direction, which bearing comprises at least two pairs of bearing surfaces for taking up axial forces acting in opposite directions, each pair comprising two bearing surfaces which are present on bearing portions which are rotatable with respect to one another, and which bearing surfaces cooperate via a lubricant, the sleeve bearing communicating with the vacuum space of the X-ray tube via at least one opening.
An X-ray tube of this kind, comprising a sleeve bearing in the shape of a helical-groove bearing, is known from EP-OS 141 476. In practice it is unavoidable that droplets of lubricant escape from the bearing. Because the amount of lubricant of such bearings is limited, this loss of lubricant may lead to the descruction of the bearing.